CN201945347U - Flowmeter pretreatment instrument - Google Patents
Flowmeter pretreatment instrument Download PDFInfo
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- CN201945347U CN201945347U CN2010206661715U CN201020666171U CN201945347U CN 201945347 U CN201945347 U CN 201945347U CN 2010206661715 U CN2010206661715 U CN 2010206661715U CN 201020666171 U CN201020666171 U CN 201020666171U CN 201945347 U CN201945347 U CN 201945347U
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Abstract
The utility model relates to a flowmeter pretreatment instrument which comprises a casing and an internal processing circuit, wherein the casing is provided with an alternating current supply hub, a signal input port and a signal output port. The flowmeter pretreatment instrument is technically characterized in that the casing is a shielding casing; an internal shielding box is arranged in the shielding casing in an electrical insulation manner; and the processing circuit is arranged in the internal shielding box in an electrical insulation manner. The flowmeter pretreatment instrument provided by the utility model has the advantages that the design is reasonable, and the casing, the internal shielding box and the processing circuit are mutually isolated, thus common-mode interference is effective inhibited; and simultaneously, a filtering circuit, an inhibition circuit, an amplitude limiting circuit, an automatic gain control circuit and the other circuits are organically combined, thus the anti-interference performance is strong, high gain amplification can be carried out on input feeble signals, and inhibition attenuation and gain automatic regulation can be carried out on input strong signals, thus the signal detection range is wider. The pretreatment instrument can be applied to non-electric quantity detection situations, thus the detection accuracy can be ensured, and the detection reliability can be greatly improved.
Description
Technical field
The utility model belongs to the non-electric charge quantity signalling detection range, especially a kind of flowmeter pre-service instrument.
Background technology
In the testing process of some non-electric charge quantity signalling, the fields such as detection of the detection of flow, revolution for example, the electric weight of its converter output is very faint, if want these feeble signals are become available signal, could use after must handling these feeble signals.Existing flowmeter can't detect these feeble signals usually, this is owing to be subjected to facing interference, the interference of noise and the factors such as interference of wave form distortion frequently, cause existing flowmeter relatively poor in accuracy of detection and reliability, for the higher occasion of some accuracy of detection, be difficult to satisfy the needs of practical application.
Summary of the invention
The purpose of this utility model is to overcome the deficiencies in the prior art, and a kind of accuracy of detection height, stable strong flowmeter pre-service instrument are provided.
The utility model solves its technical matters and takes following technical scheme to realize:
A kind of flowmeter pre-service instrument, comprise casing and treatment circuit thereof, AC power jack, signal input port and signal output port are installed on casing, described casing adopts screening housing, electrical isolation is installed an inner screening box in screening housing, and the treatment circuit electrical isolation is installed in the inner screening box.
And, be provided with manyly on the described casing to signal input port and signal output port, described treatment circuit is corresponding a plurality of with signal input port and signal output port.
And described signal output port comprises analog signal output mouth and TTL signal output port.
And, described treatment circuit comprises low-pass filter circuit, large-signal amplitude limiter circuit, balanced signal change-over circuit, automatic gain control circuit, second-order active filter circuit and the analog output circuit that is connected successively, low-pass filter circuit is connected with signal input port, and the signal output port that is provided with on analog output circuit and the housing is connected.
And, also connecting double limiting circuit and light-coupled isolation output circuit behind the described second-order active filter circuit successively, the signal output port that is provided with on light-coupled isolation output circuit and the housing is connected.
And, described balanced signal change-over circuit comprises amplifier A1 and amplifier A2, the inverting input of amplifier A1 is connected with a balanced signal, the positive input of amplifier A1 connects an end of resistance R 1, resistance R 2, the output terminal of amplifier A1 connects the other end of resistance R 2 and an end of resistance R 3, the inverting input of amplifier A2 is connected with another balanced signal, the normal phase input end of amplifier A2 connects an end of resistance R 4, and the other end of the output terminal of amplifier A2 and resistance R 3, the other end of resistance R 4 link together.
And, described automatic gain control circuit comprises amplifier A3, amplifier A4 and amplifier A5, input signal is connected to the positive input of amplifier A3, the inverting input of amplifier A3 connects an end of resistance R 5 and the drain electrode of field effect transistor V1, the source electrode of field effect transistor V1 is connected with ground, the grid of field effect transistor and resistance R 6, one end of resistance R 7 is connected, resistance R 5 is connected with the output terminal of amplifier A3 with the other end of resistance R 6, the output terminal of amplifier A3 is through capacitor C 1 coupling output, this output signal connects an end of resistance R 11 and resistance R 12, the other end of resistance R 11 connects the inverting input of amplifier A4 by diode D1, the other end of resistance R 11 connects diode cathode and ground connection, the other end of resistance R 12 is connected with the inverting input of amplifier A5 and an end of resistance R 13, the positive input of amplifier A5 is connected with ground, the output terminal of amplifier A5, the other end of resistance R 13 connects resistance R 8, the inverting input of the other end of resistance R 8 and amplifier A4, the positive pole of capacitor C 2 is connected; Working power VDD connects an end of resistance R 10, the other end of resistance R 10 is connected with an end of resistance R 9, the positive pole of stabilivolt D5, the positive pole of diode D4, the other end of resistance R 9 connects the negative pole of diode D3, the inverting input of amplifier A4 is connected, the other end of the negative pole of the negative pole of the positive pole of diode D3, diode D4, capacitor C 2 and resistance R 7 is connected to the output terminal of amplifier A4 jointly, and the normal phase input end of amplifier A4 is connected with ground.
And, also connecting a relay indicating light behind the described automatic gain control circuit, this relay indicating light is installed on the front panel of casing.
And described second-order active filter circuit also is connected with the filter frequencies selector switch that is provided with on the casing.
Advantage of the present utility model and good effect are:
The utility model is reasonable in design, adopt double-layer shielding structure, with mutually insulated between casing, inner screening box and the treatment circuit three, suppressed common mode interference effectively, circuit such as filtering, inhibition, amplitude limit and automatic gain are organically combined have very strong antijamming capability simultaneously, feeble signal for input, can carry out the amplification of high-gain to it, and, then suppress decay for the large-signal signal of importing, gain is automatically adjusted, have the area detection signal of broad.This pre-service instrument is applied to non electrical quantity and detects occasion, can guarantee the accuracy that detects to improve the reliability of testing greatly.
Description of drawings
Fig. 1 is an outward appearance front view of the present utility model;
Fig. 2 is the rear view of Fig. 1;
Fig. 3 is a circuit block diagram of the present utility model;
Fig. 4 is balanced signal change-over circuit figure;
Fig. 5 is automatic gain control circuit figure;
Fig. 6 is the synoptic diagram of the anti-common mode interference of the utility model.
Embodiment
Below in conjunction with accompanying drawing the utility model embodiment is further described:
A kind of flowmeter pre-service instrument, as shown in Figures 1 and 2, comprise casing 1 and treatment circuit thereof, on the front panel of casing, be provided with power switch 6, the signal input port 4 of power light 5 and 10 passages, filter frequencies selector switch 3, working station indicator 2, on the rear panel of casing, exchange supply hub 10, protective tube 9, the analog signal output mouth 7 of grounding ports 8 and 10 passages and TTL output port 8, outside flow signal enters inner treatment circuit circuit by the signal input on the front panel, by treatment circuit signal is handled the back by analog signal output mouth on the rear panel or the output of TTL output port.Innovation part of the present utility model is: adopt double-layer shielding structure, as shown in Figure 6, casing adopts screening housing 11, electrical isolation is installed an inner screening box 12 in screening housing, treatment circuit 13 electrical isolations are installed in the inner screening box, thereby make mutually insulated between casing, inner screening box and the treatment circuit, thereby suppressed common mode interference effectively.
Present embodiment is provided with 10 signal input ports and can handles 10 road signals simultaneously and by output port output, improve work efficiency.
Treatment circuit is installed in the inner screening box, as shown in Figure 3, comprise the low-pass filter circuit, large-signal amplitude limiter circuit, balanced signal change-over circuit, automatic gain control circuit, second-order active filter circuit and the analog output circuit that connect successively, output terminal at the second-order active filter circuit also connects double limiting circuit and light-coupled isolation output circuit successively, detect the result who handles and both can export simulating signal by analog output circuit, also can be by light-coupled isolation output circuit output TTL signal.For the ease of monitoring the duty of this testing circuit, behind automatic gain control circuit, also connect the demonstration that a relay indicating light carries out the testing circuit duty, in the present embodiment, this working station indicator adopts light emitting diode.In order to enlarge the range of application of second-order active filter circuit, increased the filter frequencies selector switch at the second-order active filter circuit, adjust different filter ranges to adapt to different application scenarios by wave filter frequency selective switch on the casing.
Low-pass filter circuit carries out low-pass filtering treatment to the signal of floating of input, will be higher than outside the various frequency signals of basic frequency more than two times are blocked in.Large-signal after the low-pass filtering treatment adopts the large-signal amplitude limiting processing that it is carried out amplitude limiting processing; Then carry out the two-stage processing and amplifying for small-signal, the first order adopts the balanced signal change-over circuit, this balanced signal change-over circuit converts balanced signal to earth signal to, what make output has enough gains to earth signal, automatic gain control circuit is adopted in the second level, and this automatic gain control circuit further amplifies signal and is processed into needed TTL signal or simulating signal automatically according to the size of signal.The signal of second-order active filter device after to processing and amplifying carries out second-order active filter, and useful signal is filtered and screens.Simulating signal after analog output circuit is handled the second-order active filter device is directly exported.Signal after the double limiting circuit is handled the second-order active filter device carries out double limiting to be handled, through light-coupled isolation output circuit output TTL signal.
Below balanced signal change-over circuit and the automatic gain control circuit that carries out the small-signal processing and amplifying is elaborated:
The annexation of balanced signal change-over circuit, as shown in Figure 4, the balanced signal IN of input
ABe connected to the inverting input of amplifier A1, the positive input of amplifier A1 connects an end of resistance R 1, resistance R 2, and the output terminal of amplifier A1 connects the other end of resistance R 2 and an end of resistance R 3; The balanced signal IN of input
BBe connected to the inverting input of amplifier A2, the normal phase input end of amplifier A2 connects an end of resistance R 4, and the other end of the output terminal of amplifier A2 and resistance R 3, the other end of resistance R 4 link together.
The principle of work of this balanced signal change-over circuit is: the balanced signal IN of input
AAnd IN
BDeliver to the inverting input of amplifier A1, A2 respectively, through synthetic output OUT after following.R flows through
1Electric current I
R1=V
INA/ R
1, R flows through
2Electric current I
R2=(V
X-V
INA)/R
2, R flows through
3Electric current I
R3=(V
INB-V
X)/R
3, R flows through
4Electric current I
R4=(V
OUT-V
INB)/R
4, make R
1=R
2=R
3=R
4=R, amplifier is an ideal amplifier, then has:
V
INA/R＝(V
X-V
INA)/R
(V
INB-V
X)/R＝(V
OUT-V
INB)/R，
To obtain behind the above-mentioned formula simultaneous solution equation:
V
Out＝2(V
INB-V
INA)；
Can know that from following formula output signal is over the ground, output valve is 2 times two input signals poor.
The annexation of automatic gain control circuit, as shown in Figure 5, input signal IN is connected to the positive input of amplifier A3, the inverting input of amplifier A3 connects an end of resistance R 5 and the drain electrode of field effect transistor V1, the source electrode of field effect transistor V1 is connected with ground, the grid of field effect transistor and resistance R 6, the end of R7 is connected, resistance R 5 is connected with the output terminal of amplifier A3 with the other end of resistance R 6, the output terminal of amplifier A3 is through capacitor C 1 coupling conduct output, this output signal connects an end of resistance R 11 and resistance R 12, the other end of resistance R 11 connects the inverting input of amplifier A4 by diode D1, anti-phase connection diode of the other end of resistance R 11 and ground connection, the other end of resistance R 12 is connected with the inverting input of amplifier A5 and an end of resistance R 13, the positive input of amplifier A5 is connected with ground, the output terminal of amplifier A5, the other end of resistance R 13 connects resistance R 8, the inverting input of the other end of resistance R 8 and amplifier A4, the positive pole of capacitor C 2 is connected; Working power VDD connects an end of resistance R 10, the other end of resistance R 10 is connected with an end of resistance R 9, the positive pole of stabilivolt D5, the positive pole of diode D4, the other end of resistance R 9 connects the negative pole of diode D3, the inverting input of amplifier A4 is connected, the other end of the negative pole of the negative pole of the positive pole of diode D3, diode D4, capacitor C 2 and resistance R 7 is connected to the output terminal of amplifier A4 jointly, and the normal phase input end of amplifier A4 is connected with ground.
The principle of work of automatic gain control circuit is as follows: after input signal is added to amplifier A3, the coupling of its output signal process C1 is as output, this output signal by D1, D2 rectification after with carry out 1 to 1 amplifying signal through amplifier A5 and enter amplifier A4 end of oppisite phase jointly, signal at this point is a pulsating direct current with certain DC component, and its DC component comes from R9.Amplifier A4 carries out Integral Processing as integrator with the pulsating direct current of input here, export a DC level afterwards, if input signal is big more, this DC level is then negative more, otherwise then negative is little, field effect transistor V1 is operated in the negative grid state, the output of amplifier A4 is negative more, equivalent resistance between leak in the source of field effect transistor V1 is big more, cause the gain of amplifier A3 low more, thereby make last output diminish, because this negative feedback makes that the amplitude of output signal is stablized.If it is big to be stabilized the scope of signal, the such circuit of available two-stage is finished jointly, facts have proved that effect is very obvious.
Through the signal that automatic gain control circuit was handled, again with the garbage signal more than further filtering two frequencys multiplication of second-order low-pass filter, its output can be used as simulation output, also can be by light-coupled isolation output circuit output TTL signal after double limiting is handled.
The principle of work that the utility model suppresses anti-common mode interference as shown in Figure 6, owing to get mutually insulated between casing, inner screening box and the treatment circuit, then there are three distributed capacitance in processing instrument, it is the capacitor C 1 between casing and the circuit, capacitor C 2 between circuit and the shielding box, the capacitor C 3 between shielding box and the casing, and Fig. 6 is equivalent circuit theory figure, in the figure, V
0Be input signal, insert amplification system, R through remote cable
HAnd R
LBe the equivalent resistance of cable, R0 is the equivalent resistance of screen layer, V
CMBe common mode interference signal, its value can reach tens volts, even goes up hectovolt, capacitor C
1Be the distributed capacitance of casing to amplifier, therefore very little because the centre has the inner screening box to be separated by, C
2Be the distributed capacitance of amplifier to shielding box, C
3Be the distributed capacitance of shielding box, because C to casing
1Impedance Z C
1=1/J ω C
1Very big, and R
0Very little, so V
CMNearly all be distributed in C
1On, C in addition
2, C
3Also to V
CMHave certain dividing potential drop, visible common mode interference is effectively suppressed.
It is emphasized that; embodiment described in the utility model is illustrative; rather than it is determinate; therefore the utility model is not limited to the embodiment described in the embodiment; every by those skilled in the art according to other embodiments that the technical solution of the utility model draws, belong to the scope of the utility model protection equally.
Claims (9)
1. flowmeter pre-service instrument, comprise casing and treatment circuit thereof, AC power jack, signal input port and signal output port are installed on casing, it is characterized in that: described casing adopts screening housing, electrical isolation is installed an inner screening box in screening housing, and the treatment circuit electrical isolation is installed in the inner screening box.
2. a kind of flowmeter pre-service instrument according to claim 1 is characterized in that: be provided with manyly to signal input port and signal output port on the described casing, described treatment circuit is corresponding a plurality of with signal input port and signal output port.
3. a kind of flowmeter pre-service instrument according to claim 1, it is characterized in that: described signal output port comprises analog signal output mouth and TTL signal output port.
4. a kind of flowmeter pre-service instrument according to claim 1, it is characterized in that: described treatment circuit comprises low-pass filter circuit, large-signal amplitude limiter circuit, balanced signal change-over circuit, automatic gain control circuit, second-order active filter circuit and the analog output circuit that is connected successively, low-pass filter circuit is connected with signal input port, and the signal output port that is provided with on analog output circuit and the housing is connected.
5. a kind of flowmeter pre-service instrument according to claim 4, it is characterized in that: also connect double limiting circuit and light-coupled isolation output circuit behind the described second-order active filter circuit successively, the signal output port that is provided with on light-coupled isolation output circuit and the housing is connected.
6. according to the treatment circuit of claim 4 or 5 described a kind of feeble signals, it is characterized in that: described balanced signal change-over circuit comprises amplifier A1 and amplifier A2, the inverting input of amplifier A1 is connected with a balanced signal, the positive input of amplifier A1 connects resistance R 1, one end of resistance R 2, the output terminal of amplifier A1 connects the other end of resistance R 2 and an end of resistance R 3, the inverting input of amplifier A2 is connected with another balanced signal, the normal phase input end of amplifier A2 connects an end of resistance R 4, the other end of the output terminal of amplifier A2 and resistance R 3, the other end of resistance R 4 links together.
7. according to the treatment circuit of claim 4 or 5 described a kind of feeble signals, it is characterized in that: described automatic gain control circuit comprises amplifier A3, amplifier A4 and amplifier A5, input signal is connected to the positive input of amplifier A3, the inverting input of amplifier A3 connects an end of resistance R 5 and the drain electrode of field effect transistor V1, the source electrode of field effect transistor V1 is connected with ground, the grid of field effect transistor and resistance R 6, one end of resistance R 7 is connected, resistance R 5 is connected with the output terminal of amplifier A3 with the other end of resistance R 6, the output terminal of amplifier A3 is through capacitor C 1 coupling output, this output signal connects an end of resistance R 11 and resistance R 12, the other end of resistance R 11 connects the inverting input of amplifier A4 by diode D1, the other end of resistance R 11 connects diode cathode and ground connection, the other end of resistance R 12 is connected with the inverting input of amplifier A5 and an end of resistance R 13, the positive input of amplifier A5 is connected with ground, the output terminal of amplifier A5, the other end of resistance R 13 connects resistance R 8, the inverting input of the other end of resistance R 8 and amplifier A4, the positive pole of capacitor C 2 is connected; Working power VDD connects an end of resistance R 10, the other end of resistance R 10 is connected with an end of resistance R 9, the positive pole of stabilivolt D5, the positive pole of diode D4, the other end of resistance R 9 connects the negative pole of diode D3, the inverting input of amplifier A4 is connected, the other end of the negative pole of the negative pole of the positive pole of diode D3, diode D4, capacitor C 2 and resistance R 7 is connected to the output terminal of amplifier A4 jointly, and the normal phase input end of amplifier A4 is connected with ground.
8. according to the treatment circuit of claim 4 or 5 described a kind of feeble signals, it is characterized in that: also connect a relay indicating light behind the described automatic gain control circuit, this relay indicating light is installed on the front panel of casing.
9. according to the treatment circuit of claim 4 or 5 described a kind of feeble signals, it is characterized in that: described second-order active filter circuit also is connected with the filter frequencies selector switch that is provided with on the casing.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN2010206661715U CN201945347U (en) | 2010-12-17 | 2010-12-17 | Flowmeter pretreatment instrument |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN2010206661715U CN201945347U (en) | 2010-12-17 | 2010-12-17 | Flowmeter pretreatment instrument |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN201945347U true CN201945347U (en) | 2011-08-24 |
Family
ID=44472686
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN2010206661715U Expired - Fee Related CN201945347U (en) | 2010-12-17 | 2010-12-17 | Flowmeter pretreatment instrument |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN201945347U (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN106370209A (en) * | 2016-11-16 | 2017-02-01 | 天津市盛丹电子技术发展有限公司 | Input and output multichannel signal conditioning device |
| CN106788383A (en) * | 2016-11-16 | 2017-05-31 | 天津市盛丹电子技术发展有限公司 | A kind of small-signal modulate circuit of non-electrical sensor |
-
2010
- 2010-12-17 CN CN2010206661715U patent/CN201945347U/en not_active Expired - Fee Related
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN106370209A (en) * | 2016-11-16 | 2017-02-01 | 天津市盛丹电子技术发展有限公司 | Input and output multichannel signal conditioning device |
| CN106788383A (en) * | 2016-11-16 | 2017-05-31 | 天津市盛丹电子技术发展有限公司 | A kind of small-signal modulate circuit of non-electrical sensor |
| CN106788383B (en) * | 2016-11-16 | 2024-01-26 | 天津市盛丹电子技术发展有限公司 | Weak signal conditioning circuit of non-electric quantity sensor |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| C14 | Grant of patent or utility model | ||
| GR01 | Patent grant | ||
| C17 | Cessation of patent right | ||
| CF01 | Termination of patent right due to non-payment of annual fee |
Granted publication date: 20110824 Termination date: 20131217 |